The reason that the button is "Maybe Later" and not "No" is so that you, the user, don't think that your only option is to agree now, regardless of how busy you are with other things, or else lose the option to do whatever it is *forever*.
It's just a little bit of #ux design to hint to you that you aren't making an irrevocable choice. That's all.
Having now explained this, please get the fuck over it.
(2/2)